1. Field of the Invention
The present invention relates to the preparation of tert-butylphenyl diphenyl phosphate. More particularly, the present invention relates to the preparation of a meta/para isomer mixed tert-butylphenyl diphenyl composition having low temperature stability.
2. Related Art
It is known to produce tert-butylphenyl diphenyl phosphate by the process of alkylating a phenol with isobutylene and thereafter phosphorylating the tert-butylphenol product to the tert-butylphenyl diphenyl phosphate product with phosphorus oxychloride.
As manufactured by the above process, the phosphate ester which is primarily composed of the para-isomer has a tendency to crystallize upon low temperature storage when produced from a tert-butylphenol composition containing a high concentration of para-tert-butylphenol (a/k/a p-tert-butylphenol).
Meta tert-alkylphenols have been prepared by the isomerization of tert-alkylphenols in the presence of trifluoromethane sulfonic acid, see U.S. Pat. No. 4,103,096 incorporated herein by reference.